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Develop ultra capacitor power supply and LiFePO4 battery power supply
Develop ultra capacitor power supply and LiFePO4 battery power supply
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Old 14th September 2018, 02:05 PM   #51
wtnh is offline wtnh  United States
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Originally Posted by iancanada View Post
Hi Wtnh,

Your PCB looks very good. I think you are very happy with your battery power supply and the sound quality.

I did some thing similar years ago. But this time, I have to take a lot of things into design consideration.

Regards,
Ian
Hi Ian - have you worked out the logic flow for the controller yet?

I started a design about a year ago to have dual LifoPO4 banks - one charging and one supplying - with a small Pic controller with relay isolation. It quickly became way too complex, particularly with having an isolated sense circuit (using a comparator) to help the logic decide when to switch banks. So I went with the simple approach I posted here, which is "good enough" for a little Allo-based DAC player.

But - I look forward to your solution because I want to build a much higher end DAC with batteries or caps for the clocks and DAC (possibly using your new Pi Fifo - keep me in mind for a GB).

It seems like the design should have some options, like music sensing to control the switching in addition to sensing battery or cap charge levels.

Cheers

Whit
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Old 14th September 2018, 02:48 PM   #52
iancanada is offline iancanada  Canada
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Develop ultra capacitor power supply and LiFePO4 battery power supply
@Whit

I'm working on the controller FW now. It's really a bit complicated. But everything is under control so far.

Yes, the charging voltage will also be monitored and managed. Not only for extending LifePO4 battery life time, but also for some "sweet spot" voltages of particular audio applications. For example, you can set the charge ending voltage at 3.30V, 3.55V or something in between for the best preferred sound quality.

How to protect relay contacts would be also part of consideration.

It will be very well integrated and I think it will be good for your high-end DAC project as an all in one power supply solution.

Regards,
Ian
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Old 14th September 2018, 02:50 PM   #53
merlin el mago is offline merlin el mago
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Ian do you have ETA, will be GB?
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Old 14th September 2018, 03:16 PM   #54
GOR3 is offline GOR3  United States
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Originally Posted by sq225917 View Post
Theredoes seem to be a bit of assumption going on in this thread as regards theaudible differences between these different types of PSU. Where's themeasurements boys?

SQ, I'm an objectivist too. That being said, have you read John Walton's (diyAudio member jackinnj) article in Linear Audio, A Comparative Overview of Power Supply Regulator Designs with Listening Tests? While the various regulators measured differently and, in listening tests, sounded differently, Walton had a difficult time correlating the measurements to the listening tests. It's a fascinating article.
In any event, and FWIW, I prefer the sound of my DAC with the master clock powered by a LiFePO4 battery rather than a regulator.


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Old 14th September 2018, 06:35 PM   #55
wtnh is offline wtnh  United States
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Originally Posted by iancanada View Post
@Whit

I'm working on the controller FW now. It's really a bit complicated. But everything is under control so far.

Yes, the charging voltage will also be monitored and managed. Not only for extending LifePO4 battery life time, but also for some "sweet spot" voltages of particular audio applications. For example, you can set the charge ending voltage at 3.30V, 3.55V or something in between for the best preferred sound quality.

How to protect relay contacts would be also part of consideration.

It will be very well integrated and I think it will be good for your high-end DAC project as an all in one power supply solution.

Regards,
Ian
I had been thinking about the relay contact current problem also. On the charging side, using a constant current/constant voltage charging IC should limit the current through the contacts. The supply side is trickier since the downstream decoupling caps could be discharged and easily arc the contacts when they close. One solution could be a second relay in series with a low value current limiting resistor. After a suitable delay, the main relay would bypass the resistor and provide a low impedance path.

Another approach could be a low Rds-on mosfet in series with the contacts to limit the inrush. Similar to special power distribution ICs which are used in hot-swap applications (although most of these have charge pumps which would inject noise). The mosfet could provide a soft start function.

Cheers

Whit
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Old 15th September 2018, 01:58 AM   #56
wtnh is offline wtnh  United States
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Originally Posted by wtnh View Post
I had been thinking about the relay contact current problem also. On the charging side, using a constant current/constant voltage charging IC should limit the current through the contacts. The supply side is trickier since the downstream decoupling caps could be discharged and easily arc the contacts when they close. One solution could be a second relay in series with a low value current limiting resistor. After a suitable delay, the main relay would bypass the resistor and provide a low impedance path.

Another approach could be a low Rds-on mosfet in series with the contacts to limit the inrush. Similar to special power distribution ICs which are used in hot-swap applications (although most of these have charge pumps which would inject noise). The mosfet could provide a soft start function.

Cheers

Whit
For the mosfet case, perhaps something like the attached....

Cheers

Whit
Attached Images
File Type: png Batt Relay Current Limit.png (79.9 KB, 379 views)
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Old 15th September 2018, 06:43 PM   #57
iancanada is offline iancanada  Canada
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Develop ultra capacitor power supply and LiFePO4 battery power supply
@Whit

I like your idea of the MOSFET solution. Very smart!

I would be glad to implement it in my design if I didn't have the relay array. Now, the array has delay relays included. The delay could be around 300ms to 1s. High current charger also has soft start feature.

Maybe I can implement your idea in my ultra capacitor power supply design later on.

Thank you so much and have a good weekend.
Ian
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Old 15th September 2018, 08:21 PM   #58
wtnh is offline wtnh  United States
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Quote:
Originally Posted by iancanada View Post
@Whit

I like your idea of the MOSFET solution. Very smart!

I would be glad to implement it in my design if I didn't have the relay array. Now, the array has delay relays included. The delay could be around 300ms to 1s. High current charger also has soft start feature.

Maybe I can implement your idea in my ultra capacitor power supply design later on.

Thank you so much and have a good weekend.
Ian
Glad you like it. The CSD17312 seems like a good choice for this because the typical Rdson (with Vgs of 3 volts) is less than 2mOhms, a lot less than typical relay contacts. The Vgsth is only 1.1 volts and it can handle 30 amps. The datasheet is here. Also, it comes in a Q5 SMD package, so not much PCB real estate needed.

Cheers

Whit
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Old 16th September 2018, 10:24 AM   #59
sontero is offline sontero  Italy
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Originally Posted by wtnh View Post
For the mosfet case, perhaps something like the attached....

Cheers

Whit

I do not understand, silicon is in series with the batteries. I'm doing it wrong?
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Old 16th September 2018, 10:35 AM   #60
KVP is offline KVP  Belgium
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